Introduction

These functions allow you to get the date and time from the server
where your PHP scripts are running. You can use these functions to format the
date and time in many different ways.

The date and time information is internally stored as a 64-bit number so
all conceivably useful dates (including negative years) are supported. The range is from about 292
billion years in the past to the same in the future.

Note:
Please keep in mind that these functions are dependent on
the locale settings of your server. Make sure to take
daylight saving time (use e.g.
$date = strtotime('+7 days', $date) and not
$date += 7*24*60*60)
and leap years into consideration when working
with these functions.